title: Degradation mechanism of monosaccharides and xylan under pyrolytic conditions with theoretic modeling on the energy profiles.
abstract: Xylan and three monosaccharides (mannose, galactose, and arabinose) were selected as model compounds to investigate the mechanism of hemicellulose pyrolysis. The evolution of several typical pyrolysis products were observed by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. Monosaccharides underwent similar pyrolysis routes involving ring opening and secondary decomposition. Breakage of the O-acetyl groups and 4-O-methylglucuronic acid units in xylan branches resulted in its different pyrolysis behavior for the formation of acetic acid, CO2, and CO. The detailed reaction pathways of the monosaccharides were studied using density functional theory calculations. Furfural formation was more favorable than the formation of 1-hydroxy-2-propanone and 4-hydroxydihydrofuran-2(3H)-one during xylose degradation. However, in the pyrolysis of mannose and galactose, formation of 5-hydroxymethyl-2-furaldehyde was preferred because of the high energy barrier of the dissociation of the hydroxymethyl group. Meanwhile, the breakage of O-acetyl groups leading to acetic acid formation easily occurred because of its lower energy barrier.
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China. srwang@zju.edu.cn
authors.forename: Shurong
authors.initials: S
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Ru
authors.forename: Haizhou
authors.initials: H
authors.lastname: Lin
authors.forename: Zhongyang
authors.initials: Z
authors.lastname: Luo
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism; D008962:Models, Theoretical; D009005:Monosaccharides / Q000378:metabolism*; D014990:Xylans / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism
chemical_list: D009005:Monosaccharides; D014990:Xylans; D002245:Carbon Dioxide; D002248:Carbon Monoxide; D014994:Xylose
keywords: DFT; Hemicellulose; Model compounds; Pyrolysis mechanism; TG-FTIR